434 REPORT OF NEW JERSEY STATE MUSEUM. 



Eyes conspicuous, moderately large and prominent. Carpus with, 

 line little elevated on upper side within. Hands suboval, on 

 elevated obtuse line on exterior side. Fingers short. Penul- 

 timate joint of all feet dilated, compressed, with minute crenge on 

 inner edge. Tarsi incurved at tip, very acute. Abdomen gradu- 

 ally attenuated, joints transverse, terminal one much smaller than 

 preceding, rounded. Length not quite 2.5 mm., and breadth a 

 little over same. (Say.) 



Remarks. — Known only from Say's account. His examples 

 were procured several years previous to 181 7, at Egg Plarbor, and 

 he thought they may possibly be the male of the common oyster 

 crab. He was also uncertain whether it inhabits oysters or not. 

 No specimens appear to have been obtained, at least in New 

 Jersey, since Say's time. 



Genus PINNOTHERES Latreille. 



The Oyster Crabs. 



Pinnotheres Latreille, Hist. Nat. Crust., Ill, 1802, p. 25. Type Cancer pisum 



Fabricius, monotypic. 

 Pinnotliera, Pinnotercs, aiict. 



Carapace smooth, subglobose, more or less membranaceous, 

 very little wider than long. Front narrow, with anterior edge 

 nearly straight. Orbits small, nearly circular. Antennules 

 obliquely transverse, large merus curved, last joint of palp joined 

 to inner edge of preceding one. Ambulatory leg's not differing 

 remarkably in length, of moderate extent. 



Two species on our coast, commensals in oysters, mussels and 

 scallops. The common oyster crab, perhaps the best known, is 

 often cooked and eaten with oysters. 



Key to the species. 



a. Carapace thicker and firmer ; surface covered with a dense pubescence. 



maculatus 



aa. Carapace of female very thin and membranaceous ; surface smooth and 



shining. ostreum 



